The inventor of the present invention already provided a dustproof mask for a nose (disclosed in published Korean Patent Application No. 10-2005-0073967), which includes a clamping unit surrounding the nasal septum (the septum of the nose) of a user, filter receiving units connected to the clamping unit, and filters respectively installed on the filter receiving units, so that the filter receiving units are attached closely to the inner walls of the nasal cavities of the user. The filters are installed at portions of the filter receiving units having the maximum diameter. In the above dustproof mask for a nose, when the clamping unit is fixed to the nasal septum, the filter receiving units formed at both tips of the clamping unit are inserted into the nasal cavities and the filters installed on the filter receiving units filter out dust from air flowing into the nasal cavities.
Korean Patent Laid-open Publication No. 10-2005-0008729 discloses a nose mask, in which double filters are installed at tips of an installation shaft and cellulose sponges are arranged in the double filters. The nose mask includes the double filters, which have an approximately flat board shape, thereby causing difficulty in circulating air and thus causing inconvenience for breathing through the nose to a user. Further, the structure for installing the double filters at the tips of the installation shaft is complicated, thus increasing the production cost of the nose mask.
Japanese Patent Laid-open Publication No. H08-71170 discloses a dustproof means for a nose. Projecting parts are formed on fixing parts of a connecting piece of the mask so that the means is not separated from the nose of a user even when a strong extrusion force, such as sneezing, is applied to the means. However, filters fill the front ends of the nasal cavities having a comparatively small diameter and have a flat board shape, thereby having a small surface area and thus causing inconvenience for breathing through the nose to the user.
Further, Japanese Patent Laid-open Publication No. H11-137702 discloses a nose mask, in which the surface area of the filters is increased so as to give a user convenience for breathing through the nose. However, the filters have a hollow semi-ellipsoidal shape such that the diameter of the middle portion of a main body of each of the filters is the same as that of the front end of the main body of each of the filters. In the above nose mask, since the diameter of the main wall of each of the filters cannot coincide with the inner diameter of the nasal cavity of a user, non-filtered air may be inhaled through gaps between the filters and the nasal cavities during breathing. Further, the nose mask does not include any unit for holding the mask in the nose, and thus may be separated from the nose due to sneezing.
Accordingly, the inventor provided a dustproof mask for nose disclosed in Korean Patent Application No. 10-2005-0125179. In the mask, nipple-shaped connectors are formed at tips of a clamping unit and filters are installed directly on the connectors so that the filters are located in the nasal cavities of a user, thus giving the user convenience for breathing through the nose. However, the mask is disadvantageous in that the filters installed at the tips of the clamping unit have an approximately flat board shape and thus have a comparatively small surface area. Further, the mask is disadvantageous in that the clamping unit has an insufficient force for holding the nasal septum.